ANM falls into the category of off-grid compressive sensing, which provides a powerful mathematical tool for eliminating the basis mismatch and power leakage problem, while offering high-accuracy angle estimation [1]}, [2]}. To this end, we start the definition of the atomic set [1]}, [4]}, [2]}, [6]} for our estimation problem:
\(\mathcal {A} \triangleq \lbrace \alpha _y(x_1, x_2) \otimes \alpha _z(x_2), x_1 \in [0, \pi ], x_2 \in [-\pi /2, \pi /2] \rbrace ,\) 
